Asthma sufferers who regularly use steroid inhalers to ease their breathing problems also lower their risk of dying from the disease, a large new study concludes.
Doctors have been uncertain until now whether treating asthma with inhaled steroids actually saves lives.
Inhaled steroids are widely used to treat asthma. They reduce the inflammation that causes airways to contract and clog and make breathing difficult.
Over time, they make the airways less sensitive to the pollen, smoke or other things that trigger asthma attacks.
"Physicians have known all along that these medications are very effective. Now with this new data, they know that they can actually save the lives of their patients," said Samy Suissa of McGill University in Montreal, one of the researchers whose study was reported in Thursday's New England Journal of Medicine.
About 17.3 million Americans suffer from asthma, and about 5,400 people die from the disease each year, according to the Centers for Disease Control and Prevention.
The study looked at medical records for 30,569 people who were treated for asthma in the Canadian province of Saskatchewan between 1975 and 1991 and followed them until 1997.
The researchers compared inhaled steroid use among 66 who died with that among 2,681 asthma patients who survived. Those in the comparison group averaged one-third more inhaled steroids a year than those who died.
The researchers calculated that the rate of death from asthma decreased by 21 percent with each additional canister of inhaled steroids used during the year.
Suissa said inhaled steroids are most effective if patients use about six canisters a year. Those who died averaged just over one a year.
Suissa said the benefits were achieved with low-dose inhaled steroids. He said Americans are particularly wary of inhaled steroids because of the possible side effects, such as stunted growth in children, osteoporosis, glaucoma and cataracts.
"Clearly the doses we're talking about, there is no evidence of any significant side effects at all," Suissa said.
Researchers also warned that regular use is important. The study showed that patients who stopped using inhaled steroids were five times more likely to die of asthma than those who continued to use them regularly.
The study did not look at another inhaler — bronchodilators — used by asthma sufferers to quickly open airways during sudden attacks.
Dr. Norman H. Edelman of the American Lung Association said the study conveys an important message. Despite recommendations for their use, "it's generally agreed that we still underuse inhalant steroids in patients with asthma," he said.
The study was funded by the Medical Research Council of Canada and several drug companies. Suissa is a consultant to one of the companies, Boehringer Ingelheim.
On the Net: New England Journal of Medicine: www.nejm.org
National Heart, Lung and Blood Institute: www.nhlbi.nih.gov
American Lung Association: www.lungusa.org/asthma